So it turns out there are some painful edges if you start trying to
do SQLAlchemy declarative ORM classes in an existing Django app.
(For example, if you're gradually replacing the Django ORM in your code with Sqlalchemy ORM). It boils down to:

Django can be run under any WSGI server, which means you can use it in
a WSGI pipeline. Deploying Django under mod_wsgi is well documented,
but sometimes you want to test your WSGI pipeline on a local server
without mucking with configuring nginx or apache,
and/or try out some ...